Tensor interaction constraints fromβ-decay recoil spin asymmetry of trapped atoms

Abstract

We have measured the angular distribution of recoiling daughter nuclei emitted from the Gamow-Teller β decay of spin-polarized 80 Rb. The asymmetry of this distribution vanishes to lowest order in the standard model (SM) in pure Gamow-Teller decays, producing an observable very sensitive to new interactions. We measure the non-SM contribution to the asymmetry to be A T = 0.015 ± 0.029 (stat) ±0.019 (syst), consistent with the SM prediction. We constrain higher-order SM corrections using the measured momentum dependence of the asymmetry, and their remaining uncertainty dominates the systematic error. Future progress in determining the weak magnetism term theoretically or experimentally would reduce the final errors. We describe the resulting constraints on fundamental four-Fermi tensor interactions.

Measurement of theβ-asymmetry parameter ofCu67in search for tensor-type currents in the weak interaction

“…[3]). Many recent experimental efforts try to improve the sensitivity to these non-standard model weak currents in searches for differences of experimental observables from their standard model predictions in both neutron decay [4][5][6][7][8][9][10] and nuclear β decay [2,[11][12][13][14][15][16][17][18].…”

Limits on tensor-type weak currents from nuclear and neutronβdecays

“…We choose not to include the result of ref. [39] because their bounds are dominated by the limited knowledge of the recoil-order corrections.…”

Atomic physics techniques for studying nuclear ground state properties, fundamental interactions and symmetries: status and perspectives

“…The beta-neutrino correlation coefficient a is determined by observing the recoil ion in coincidence with the beta particle. These experiments applying a magneto-optical trap (MOT) have been pioneered at TRIUMF by the group of Behr [191] with the study of 38m K. Since then, experiments have been performed with laser traps for 37 K [192] and for 80 Rb [193] at TRIUMF, and for 21 Na at Berkeley [194]. At TRIμP in Groningen, similar experiments on 21 Na are in the commissioning stage [195] as reported by Duurt Johan van der Hoek at the conference in Poznan.…”